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Polyvinyl alcohol-stabilized 1,3-diene/ (meth)acrylate copolymers

Imported: 25 Feb '17 | Published: 06 Aug '02

Theo Mayer, Reinhard Härzschel

USPTO - Utility Patents

Abstract

The invention discloses polyvinyl alcohol-stabilized copolymers of 1,3-dienes with methacrylates and/or acrylates in the form of their aqueous polymer dispersions or polymer powders redispersible in water, and to a process for their preparation and their use.

Claims

1. An emulsifier- and solvent-free copolymer, stabilized with nonionic polyvinyl alcohol as a protective colloid, of 1,3-butadiene and/or isoprene with a methacrylate of a C

1-10 straight chain or branched alcohol and/or an acrylate of a C

1-10 straight chain or branched alcohol, in the form of its aqueous polymer dispersion or polymer powder redispersible in water, obtainable by emulsion polymerization and optionally drying of the polymer dispersion obtainable thereby, from 10 to 100% by weight of the amount of polyvinyl alcohol being initially introduced before the initiation of the polymerization and the remaining amount being metered in during polymerization, and the addition of the polyvinyl alcohol and of the comonomers being controlled in such a way that, during the polymerization, the amount of protective colloid is always from 1 to 70% by weight of the total amount of free comonomers.

2. A process for the preparation of emulsifier- and solvent-free copolymers, stabilized with polyvinyl alcohol as a protective colloid, of 1,3-butadiene and/or isoprene with a methacrylate of a C

1-10 straight chain or branched alcohol and/or an acrylate of a C

1-10 straight chain or branched alcohol, in the form of their aqueous polymer dispersions or polymer powders redispersible in water, by emulsion polymerization in the presence of from 1 to 15% by weight, based on the total weight of the monomers, of at least one polyvinyl alcohols and optionally drying of the polymer dispersions obtainable thereby, from 10 to 100% by weight of the amount of polyvinyl alcohol being initially introduced before the initiation of the polymerization and the remaining amount being metered in during polymerization, and the addition of polyvinyl alcohol and of the comonomers being controlled in such a way that, during the polymerization the amount of protective colloid is always from 1 to 70% by weight of the total amount of free comonomers.

3. The process as claimed in claim 2, wherein mixtures comprising from 20 to 80% by weight of (meth)acrylates and from 80 to 20% by weight of 1,3-diene are polymerized, it being possible for the mixtures optionally also to contain one or more of the above-mentioned auxiliary monomers in the stated amounts, and the amounts in % by weight summing to 100% by weight.

4. The process as claimed in claim 2, wherein the methacrylates and acrylates copolymerized are at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, tert-butyl acrylate, tert-butyl methacrylate and 2-ethylhexyl acrylate.

5. The process as claimed of claim 2, wherein 1,3-butadiene and methyl methacrylate are copolymerized.

6. The process as claimed in claim 2, wherein the polyvinyl alcohol used comprises at least one member selected from the group consisting of the partially hydrolyzed polyvinyl acetates and partially hydrolyzed polyvinyl esters which have been rendered hydrophobic.

7. The process as claimed in claim 2, wherein the polyvinyl alcohol used comprises partially hydrolyzed polyvinyl acetates having a degree of hydrolysis of from 80 to 95 mol % and a Höppler viscosity of from 1 to 30 mPas.

8. The process as claimed in claim 2, wherein the polyvinyl alcohol used comprises partially hydrolyzed polyvinyl esters which have been rendered hydrophobic and, in the form of a 2% strength aqueous solution, produce a surface tension of ≦40 mN/m.

9. The process as claimed in claim 8 wherein partially hydrolyzed polyvinyl acetates having from 84 to 92 mol % of vinyl alcohol units and from 0.1 to 10% by weight of units which are derived from vinyl esters of an alpha-branched carboxylic acid having 5 or 9 to 11 carbon atoms in the acid radical, isopropenyl acetate and ethene are used.

10. The process as claimed in claim 2, wherein a combination of polyvinyl ester which has been rendered hydrophobic and partially hydrolyzed polyvinyl acetate is used as the polyvinyl alcohol.

11. The process as claimed in claim 2, wherein the polymerization is carried out in the presence of regulators.

12. The process as claimed in claim 11, wherein the regulator used comprises at least one substance selected from the group consisting of n-dodecyl mercaptan, tert-dodecyl mercaptan, mercaptopropionic acid, methyl mercaptopropionate, isopropanol and acetaldehyde.

13. The process as claimed in claim 2, wherein the aqueous dispersions obtained thereby are dried by means of fluidized-bed drying, freeze-drying or spray-drying.

14. The process as claimed in claim 2, wherein the total amount of protective colloid and from 5 to 25% by weight of the total amount of comonomer are initially introduced and the remaining amount of comonomer is metered in during polymerization.

15. The process as claimed in claim 2, wherein the total amount of protective colloid and the total amount of comonomer are initially introduced before the initiation of polymerization and are polymerized in the presence of a regulator.

16. The process as claimed in claim 2, wherein some of the amount of comonomer and some of the amount of regulator are initially introduced, with initial introduction of all of the protective colloid or with initial introduction of some of the protective colloid, and the remainder in each case is metered in.